The present invention relates to high density semiconductor packages. More particularly, the present invention relates to high density semiconductor packages and methods for making them.
Semiconductor packaging techniques are well known. In conventional packaged devices, a die is attached to a substrate, such as, for example, a lead frame, and contacts of the die and lead frame are electrically connected together. A heat sink may also be affixed to the die. The die and heat sink arc then completely encapsulated, using an overmold (a heated container with a cavity), with a molded plastic material. An example of such a conventional packaged device may be found in U.S. Pat. No. 5,901,041 (Davies et al.).
Other conventional methodologies include mounting and electrically connecting a semiconductor die to a lead frame and also incorporating heat conductive areas, such as columns, to assist in removing heat from the semiconductor die. The semiconductor die, the heat conductive columns, and a portion of the lead frame are then encapsulated. An example of such a conventional packaged device may be found in U.S. Pat. No. 5,200,809 (Kwon).
Yet other conventional methodologies include packaging the die so as to leave one surface exposed. Examples of such conventional die packages may be found in U.S. Pat. No. 5,894,108 (Mostafazadeh et al.), U.S Pat. No. 5,604,376 (Hamburgen et al.), U.S Pat. No. 5,450,283 (Lin et al.), and U.S. Pat. No. 5,177,669 (Juskey et al.).
All of the aforementioned conventional semiconductor packages include a single semiconductor die which is either partially or completely encapsulated with a molded plastic material. Other conventional semiconductor packages include more than one semiconductor die encapsulated by a molded plastic material. Examples of such high density semiconductor packages may be found in U.S. Pat. No. 5,843,807 (Burns) and U.S. Pat. No. 6,049,123 (Burns). One disadvantage of the high density semiconductor packages described in Burns is that the overall package thickness is relatively large, whereas thinner high density packages would be preferable.
What is needed is a relatively thin a high density semiconductor package which has good heat dissipation characteristics.
The invention provides a relatively thin high density semiconductor package having good heat dissipation characteristics. The package includes a first and a second lead frame, each lead frame including a plurality of fingers, a first and a second semiconductor die electrically connected to the lead frames, and an encapsulating material partially encapsulating the fingers and the semiconductor dies in a manner which leaves surfaces of the semiconductor dies exposed.
The invention further provides a method of fabricating a high density semiconductor package. The method includes the acts of attaching a first semiconductor die to a first lead frame and a second semiconductor die to a second lead frame, each lead frame including a plurality of fingers, electrically commenting the fingers of the first lead frame to the first semiconductor die and the fingers of the second lead fame to the second semiconductor die, and encapsulating portions of the fingers and the semiconductor dies in a manner which leaves a surface of each semiconductor die exposed.